96 didn't have the load valve for the rear brakes, but, it likely does have rear abs. If it started doing this right after having the rear brakes done, need to pull the drums, and see what ya got? Were the drums in good shape? Were they turned when the shoes were replaced? Or the shoes/springs on there correctly? (short shoe goes in front.)

 

thanks for the response/input.
new drums & shoes, everything put on right some discussion about wrong shoes (ceramic) but the place that did the work are local, honest, been doing this for years.
have bought a jegs manual valve like on race cars - not installed yet but maybe...... ? been driving us nuts for some time!

 

Could be a bad proportioning valve. Sending to much pressure to the rear.

 

ah, my bad - should have specified.
changed proportioning valve twice with used ones (cannot get new for 96) also changed master cylinder

 

It could be the combination valve then that controls the ABS

 

On the ones with rear abs, it's just a dump valve...... I don't think it could cause this particular problem.

Have you taken it back to the shop that did the work? What do they think is going on?

 

True but the valve can get stuck allowing full fluid to be put to the rear from my understanding.

 

Proportioning valve does the duty of limiting pressure, the dump valve just drops pressure to essentially zero, when the solenoids open the valves....

 

What I'm getting at is the ABS isn't working :b when my ABS wasn't working the rest would lock up with little brake pressure

 

Rear ABS on these trucks was never really worth much.